arch/ia64/mm/init.c

   1 /*
   2  * Initialize MMU support.
   3  *
   4  * Copyright (C) 1998-2003 Hewlett-Packard Co
   5  *      David Mosberger-Tang <davidm@hpl.hp.com>
   6  */
   7 #include <linux/config.h>
   8 #include <linux/kernel.h>
   9 #include <linux/init.h>
  10
  11 #include <linux/bootmem.h>
  12 #include <linux/efi.h>
  13 #include <linux/elf.h>
  14 #include <linux/mm.h>
  15 #include <linux/mmzone.h>
  16 #include <linux/module.h>
  17 #include <linux/personality.h>
  18 #include <linux/reboot.h>
  19 #include <linux/slab.h>
  20 #include <linux/swap.h>
  21 #include <linux/proc_fs.h>
  22 #include <linux/bitops.h>
  23
  24 #include <asm/a.out.h>
  25 #include <asm/dma.h>
  26 #include <asm/ia32.h>
  27 #include <asm/io.h>
  28 #include <asm/machvec.h>
  29 #include <asm/numa.h>
  30 #include <asm/patch.h>
  31 #include <asm/pgalloc.h>
  32 #include <asm/sal.h>
  33 #include <asm/sections.h>
  34 #include <asm/system.h>
  35 #include <asm/tlb.h>
  36 #include <asm/uaccess.h>
  37 #include <asm/unistd.h>
  38 #include <asm/mca.h>
  39
  40 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
  41
  42 DEFINE_PER_CPU(unsigned long *, __pgtable_quicklist);
  43 DEFINE_PER_CPU(long, __pgtable_quicklist_size);
  44
  45 extern void ia64_tlb_init (void);
  46
  47 unsigned long MAX_DMA_ADDRESS = PAGE_OFFSET + 0x100000000UL;
  48
  49 #ifdef CONFIG_VIRTUAL_MEM_MAP
  50 unsigned long vmalloc_end = VMALLOC_END_INIT;
  51 EXPORT_SYMBOL(vmalloc_end);
  52 struct page *vmem_map;
  53 EXPORT_SYMBOL(vmem_map);
  54 #endif
  55
  56 struct page *zero_page_memmap_ptr;      /* map entry for zero page */
  57 EXPORT_SYMBOL(zero_page_memmap_ptr);
  58
  59 #define MIN_PGT_PAGES                   25UL
  60 #define MAX_PGT_FREES_PER_PASS          16L
  61 #define PGT_FRACTION_OF_NODE_MEM        16
  62
  63 static inline long
  64 max_pgt_pages(void)
  65 {
  66         u64 node_free_pages, max_pgt_pages;
  67
  68 #ifndef CONFIG_NUMA
  69         node_free_pages = nr_free_pages();
  70 #else
  71         node_free_pages = nr_free_pages_pgdat(NODE_DATA(numa_node_id()));
  72 #endif
  73         max_pgt_pages = node_free_pages / PGT_FRACTION_OF_NODE_MEM;
  74         max_pgt_pages = max(max_pgt_pages, MIN_PGT_PAGES);
  75         return max_pgt_pages;
  76 }
  77
  78 static inline long
  79 min_pages_to_free(void)
  80 {
  81         long pages_to_free;
  82
  83         pages_to_free = pgtable_quicklist_size - max_pgt_pages();
  84         pages_to_free = min(pages_to_free, MAX_PGT_FREES_PER_PASS);
  85         return pages_to_free;
  86 }
  87
  88 void
  89 check_pgt_cache(void)
  90 {
  91         long pages_to_free;
  92
  93         if (unlikely(pgtable_quicklist_size <= MIN_PGT_PAGES))
  94                 return;
  95
  96         preempt_disable();
  97         while (unlikely((pages_to_free = min_pages_to_free()) > 0)) {
  98                 while (pages_to_free--) {
  99                         free_page((unsigned long)pgtable_quicklist_alloc());
 100                 }
 101                 preempt_enable();
 102                 preempt_disable();
 103         }
 104         preempt_enable();
 105 }
 106
 107 void
 108 lazy_mmu_prot_update (pte_t pte)
 109 {
 110         unsigned long addr;
 111         struct page *page;
 112
 113         if (!pte_exec(pte))
 114                 return;                         /* not an executable page... */
 115
 116         page = pte_page(pte);
 117         addr = (unsigned long) page_address(page);
 118
 119         if (test_bit(PG_arch_1, &page->flags))
 120                 return;                         /* i-cache is already coherent with d-cache */
 121
 122         flush_icache_range(addr, addr + PAGE_SIZE);
 123         set_bit(PG_arch_1, &page->flags);       /* mark page as clean */
 124 }
 125
 126 inline void
 127 ia64_set_rbs_bot (void)
 128 {
 129         unsigned long stack_size = current->signal->rlim[RLIMIT_STACK].rlim_max & -16;
 130
 131         if (stack_size > MAX_USER_STACK_SIZE)
 132                 stack_size = MAX_USER_STACK_SIZE;
 133         current->thread.rbs_bot = STACK_TOP - stack_size;
 134 }
 135
 136 /*
 137  * This performs some platform-dependent address space initialization.
 138  * On IA-64, we want to setup the VM area for the register backing
 139  * store (which grows upwards) and install the gateway page which is
 140  * used for signal trampolines, etc.
 141  */
 142 void
 143 ia64_init_addr_space (void)
 144 {
 145         struct vm_area_struct *vma;
 146
 147         ia64_set_rbs_bot();
 148
 149         /*
 150          * If we're out of memory and kmem_cache_alloc() returns NULL, we simply ignore
 151          * the problem.  When the process attempts to write to the register backing store
 152          * for the first time, it will get a SEGFAULT in this case.
 153          */
 154         vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
 155         if (vma) {
 156                 memset(vma, 0, sizeof(*vma));
 157                 vma->vm_mm = current->mm;
 158                 vma->vm_start = current->thread.rbs_bot & PAGE_MASK;
 159                 vma->vm_end = vma->vm_start + PAGE_SIZE;
 160                 vma->vm_page_prot = protection_map[VM_DATA_DEFAULT_FLAGS & 0x7];
 161                 vma->vm_flags = VM_DATA_DEFAULT_FLAGS | VM_GROWSUP;
 162                 down_write(&current->mm->mmap_sem);
 163                 if (insert_vm_struct(current->mm, vma)) {
 164                         up_write(&current->mm->mmap_sem);
 165                         kmem_cache_free(vm_area_cachep, vma);
 166                         return;
 167                 }
 168                 up_write(&current->mm->mmap_sem);
 169         }
 170
 171         /* map NaT-page at address zero to speed up speculative dereferencing of NULL: */
 172         if (!(current->personality & MMAP_PAGE_ZERO)) {
 173                 vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
 174                 if (vma) {
 175                         memset(vma, 0, sizeof(*vma));
 176                         vma->vm_mm = current->mm;
 177                         vma->vm_end = PAGE_SIZE;
 178                         vma->vm_page_prot = __pgprot(pgprot_val(PAGE_READONLY) | _PAGE_MA_NAT);
 179                         vma->vm_flags = VM_READ | VM_MAYREAD | VM_IO | VM_RESERVED;
 180                         down_write(&current->mm->mmap_sem);
 181                         if (insert_vm_struct(current->mm, vma)) {
 182                                 up_write(&current->mm->mmap_sem);
 183                                 kmem_cache_free(vm_area_cachep, vma);
 184                                 return;
 185                         }
 186                         up_write(&current->mm->mmap_sem);
 187                 }
 188         }
 189 }
 190
 191 void
 192 free_initmem (void)
 193 {
 194         unsigned long addr, eaddr;
 195
 196         addr = (unsigned long) ia64_imva(__init_begin);
 197         eaddr = (unsigned long) ia64_imva(__init_end);
 198         while (addr < eaddr) {
 199                 ClearPageReserved(virt_to_page(addr));
 200                 set_page_count(virt_to_page(addr), 1);
 201                 free_page(addr);
 202                 ++totalram_pages;
 203                 addr += PAGE_SIZE;
 204         }
 205         printk(KERN_INFO "Freeing unused kernel memory: %ldkB freed\n",
 206                (__init_end - __init_begin) >> 10);
 207 }
 208
 209 void
 210 free_initrd_mem (unsigned long start, unsigned long end)
 211 {
 212         struct page *page;
 213         /*
 214          * EFI uses 4KB pages while the kernel can use 4KB or bigger.
 215          * Thus EFI and the kernel may have different page sizes. It is
 216          * therefore possible to have the initrd share the same page as
 217          * the end of the kernel (given current setup).
 218          *
 219          * To avoid freeing/using the wrong page (kernel sized) we:
 220          *      - align up the beginning of initrd
 221          *      - align down the end of initrd
 222          *
 223          *  |             |
 224          *  |=============| a000
 225          *  |             |
 226          *  |             |
 227          *  |             | 9000
 228          *  |/////////////|
 229          *  |/////////////|
 230          *  |=============| 8000
 231          *  |///INITRD////|
 232          *  |/////////////|
 233          *  |/////////////| 7000
 234          *  |             |
 235          *  |KKKKKKKKKKKKK|
 236          *  |=============| 6000
 237          *  |KKKKKKKKKKKKK|
 238          *  |KKKKKKKKKKKKK|
 239          *  K=kernel using 8KB pages
 240          *
 241          * In this example, we must free page 8000 ONLY. So we must align up
 242          * initrd_start and keep initrd_end as is.
 243          */
 244         start = PAGE_ALIGN(start);
 245         end = end & PAGE_MASK;
 246
 247         if (start < end)
 248                 printk(KERN_INFO "Freeing initrd memory: %ldkB freed\n", (end - start) >> 10);
 249
 250         for (; start < end; start += PAGE_SIZE) {
 251                 if (!virt_addr_valid(start))
 252                         continue;
 253                 page = virt_to_page(start);
 254                 ClearPageReserved(page);
 255                 set_page_count(page, 1);
 256                 free_page(start);
 257                 ++totalram_pages;
 258         }
 259 }
 260
 261 /*
 262  * This installs a clean page in the kernel's page table.
 263  */
 264 struct page *
 265 put_kernel_page (struct page *page, unsigned long address, pgprot_t pgprot)
 266 {
 267         pgd_t *pgd;
 268         pud_t *pud;
 269         pmd_t *pmd;
 270         pte_t *pte;
 271
 272         if (!PageReserved(page))
 273                 printk(KERN_ERR "put_kernel_page: page at 0x%p not in reserved memory\n",
 274                        page_address(page));
 275
 276         pgd = pgd_offset_k(address);            /* note: this is NOT pgd_offset()! */
 277
 278         spin_lock(&init_mm.page_table_lock);
 279         {
 280                 pud = pud_alloc(&init_mm, pgd, address);
 281                 if (!pud)
 282                         goto out;
 283
 284                 pmd = pmd_alloc(&init_mm, pud, address);
 285                 if (!pmd)
 286                         goto out;
 287                 pte = pte_alloc_map(&init_mm, pmd, address);
 288                 if (!pte)
 289                         goto out;
 290                 if (!pte_none(*pte)) {
 291                         pte_unmap(pte);
 292                         goto out;
 293                 }
 294                 set_pte(pte, mk_pte(page, pgprot));
 295                 pte_unmap(pte);
 296         }
 297   out:  spin_unlock(&init_mm.page_table_lock);
 298         /* no need for flush_tlb */
 299         return page;
 300 }
 301
 302 static void
 303 setup_gate (void)
 304 {
 305         struct page *page;
 306
 307         /*
 308          * Map the gate page twice: once read-only to export the ELF
 309          * headers etc. and once execute-only page to enable
 310          * privilege-promotion via "epc":
 311          */
 312         page = virt_to_page(ia64_imva(__start_gate_section));
 313         put_kernel_page(page, GATE_ADDR, PAGE_READONLY);
 314 #ifdef HAVE_BUGGY_SEGREL
 315         page = virt_to_page(ia64_imva(__start_gate_section + PAGE_SIZE));
 316         put_kernel_page(page, GATE_ADDR + PAGE_SIZE, PAGE_GATE);
 317 #else
 318         put_kernel_page(page, GATE_ADDR + PERCPU_PAGE_SIZE, PAGE_GATE);
 319         /* Fill in the holes (if any) with read-only zero pages: */
 320         {
 321                 unsigned long addr;
 322
 323                 for (addr = GATE_ADDR + PAGE_SIZE;
 324                      addr < GATE_ADDR + PERCPU_PAGE_SIZE;
 325                      addr += PAGE_SIZE)
 326                 {
 327                         put_kernel_page(ZERO_PAGE(0), addr,
 328                                         PAGE_READONLY);
 329                         put_kernel_page(ZERO_PAGE(0), addr + PERCPU_PAGE_SIZE,
 330                                         PAGE_READONLY);
 331                 }
 332         }
 333 #endif
 334         ia64_patch_gate();
 335 }
 336
 337 void __devinit
 338 ia64_mmu_init (void *my_cpu_data)
 339 {
 340         unsigned long psr, pta, impl_va_bits;
 341         extern void __devinit tlb_init (void);
 342
 343 #ifdef CONFIG_DISABLE_VHPT
 344 #       define VHPT_ENABLE_BIT  0
 345 #else
 346 #       define VHPT_ENABLE_BIT  1
 347 #endif
 348
 349         /* Pin mapping for percpu area into TLB */
 350         psr = ia64_clear_ic();
 351         ia64_itr(0x2, IA64_TR_PERCPU_DATA, PERCPU_ADDR,
 352                  pte_val(pfn_pte(__pa(my_cpu_data) >> PAGE_SHIFT, PAGE_KERNEL)),
 353                  PERCPU_PAGE_SHIFT);
 354
 355         ia64_set_psr(psr);
 356         ia64_srlz_i();
 357
 358         /*
 359          * Check if the virtually mapped linear page table (VMLPT) overlaps with a mapped
 360          * address space.  The IA-64 architecture guarantees that at least 50 bits of
 361          * virtual address space are implemented but if we pick a large enough page size
 362          * (e.g., 64KB), the mapped address space is big enough that it will overlap with
 363          * VMLPT.  I assume that once we run on machines big enough to warrant 64KB pages,
 364          * IMPL_VA_MSB will be significantly bigger, so this is unlikely to become a
 365          * problem in practice.  Alternatively, we could truncate the top of the mapped
 366          * address space to not permit mappings that would overlap with the VMLPT.
 367          * --davidm 00/12/06
 368          */
 369 #       define pte_bits                 3
 370 #       define mapped_space_bits        (3*(PAGE_SHIFT - pte_bits) + PAGE_SHIFT)
 371         /*
 372          * The virtual page table has to cover the entire implemented address space within
 373          * a region even though not all of this space may be mappable.  The reason for
 374          * this is that the Access bit and Dirty bit fault handlers perform
 375          * non-speculative accesses to the virtual page table, so the address range of the
 376          * virtual page table itself needs to be covered by virtual page table.
 377          */
 378 #       define vmlpt_bits               (impl_va_bits - PAGE_SHIFT + pte_bits)
 379 #       define POW2(n)                  (1ULL << (n))
 380
 381         impl_va_bits = ffz(~(local_cpu_data->unimpl_va_mask | (7UL << 61)));
 382
 383         if (impl_va_bits < 51 || impl_va_bits > 61)
 384                 panic("CPU has bogus IMPL_VA_MSB value of %lu!\n", impl_va_bits - 1);
 385
 386         /* place the VMLPT at the end of each page-table mapped region: */
 387         pta = POW2(61) - POW2(vmlpt_bits);
 388
 389         if (POW2(mapped_space_bits) >= pta)
 390                 panic("mm/init: overlap between virtually mapped linear page table and "
 391                       "mapped kernel space!");
 392         /*
 393          * Set the (virtually mapped linear) page table address.  Bit
 394          * 8 selects between the short and long format, bits 2-7 the
 395          * size of the table, and bit 0 whether the VHPT walker is
 396          * enabled.
 397          */
 398         ia64_set_pta(pta | (0 << 8) | (vmlpt_bits << 2) | VHPT_ENABLE_BIT);
 399
 400         ia64_tlb_init();
 401
 402 #ifdef  CONFIG_HUGETLB_PAGE
 403         ia64_set_rr(HPAGE_REGION_BASE, HPAGE_SHIFT << 2);
 404         ia64_srlz_d();
 405 #endif
 406 }
 407
 408 #ifdef CONFIG_VIRTUAL_MEM_MAP
 409
 410 int
 411 create_mem_map_page_table (u64 start, u64 end, void *arg)
 412 {
 413         unsigned long address, start_page, end_page;
 414         struct page *map_start, *map_end;
 415         int node;
 416         pgd_t *pgd;
 417         pud_t *pud;
 418         pmd_t *pmd;
 419         pte_t *pte;
 420
 421         map_start = vmem_map + (__pa(start) >> PAGE_SHIFT);
 422         map_end   = vmem_map + (__pa(end) >> PAGE_SHIFT);
 423
 424         start_page = (unsigned long) map_start & PAGE_MASK;
 425         end_page = PAGE_ALIGN((unsigned long) map_end);
 426         node = paddr_to_nid(__pa(start));
 427
 428         for (address = start_page; address < end_page; address += PAGE_SIZE) {
 429                 pgd = pgd_offset_k(address);
 430                 if (pgd_none(*pgd))
 431                         pgd_populate(&init_mm, pgd, alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE));
 432                 pud = pud_offset(pgd, address);
 433
 434                 if (pud_none(*pud))
 435                         pud_populate(&init_mm, pud, alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE));
 436                 pmd = pmd_offset(pud, address);
 437
 438                 if (pmd_none(*pmd))
 439                         pmd_populate_kernel(&init_mm, pmd, alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE));
 440                 pte = pte_offset_kernel(pmd, address);
 441
 442                 if (pte_none(*pte))
 443                         set_pte(pte, pfn_pte(__pa(alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE)) >> PAGE_SHIFT,
 444                                              PAGE_KERNEL));
 445         }
 446         return 0;
 447 }
 448
 449 struct memmap_init_callback_data {
 450         struct page *start;
 451         struct page *end;
 452         int nid;
 453         unsigned long zone;
 454 };
 455
 456 static int
 457 virtual_memmap_init (u64 start, u64 end, void *arg)
 458 {
 459         struct memmap_init_callback_data *args;
 460         struct page *map_start, *map_end;
 461
 462         args = (struct memmap_init_callback_data *) arg;
 463         map_start = vmem_map + (__pa(start) >> PAGE_SHIFT);
 464         map_end   = vmem_map + (__pa(end) >> PAGE_SHIFT);
 465
 466         if (map_start < args->start)
 467                 map_start = args->start;
 468         if (map_end > args->end)
 469                 map_end = args->end;
 470
 471         /*
 472          * We have to initialize "out of bounds" struct page elements that fit completely
 473          * on the same pages that were allocated for the "in bounds" elements because they
 474          * may be referenced later (and found to be "reserved").
 475          */
 476         map_start -= ((unsigned long) map_start & (PAGE_SIZE - 1)) / sizeof(struct page);
 477         map_end += ((PAGE_ALIGN((unsigned long) map_end) - (unsigned long) map_end)
 478                     / sizeof(struct page));
 479
 480         if (map_start < map_end)
 481                 memmap_init_zone((unsigned long)(map_end - map_start),
 482                                  args->nid, args->zone, page_to_pfn(map_start));
 483         return 0;
 484 }
 485
 486 void
 487 memmap_init (unsigned long size, int nid, unsigned long zone,
 488              unsigned long start_pfn)
 489 {
 490         if (!vmem_map)
 491                 memmap_init_zone(size, nid, zone, start_pfn);
 492         else {
 493                 struct page *start;
 494                 struct memmap_init_callback_data args;
 495
 496                 start = pfn_to_page(start_pfn);
 497                 args.start = start;
 498                 args.end = start + size;
 499                 args.nid = nid;
 500                 args.zone = zone;
 501
 502                 efi_memmap_walk(virtual_memmap_init, &args);
 503         }
 504 }
 505
 506 int
 507 ia64_pfn_valid (unsigned long pfn)
 508 {
 509         char byte;
 510         struct page *pg = pfn_to_page(pfn);
 511
 512         return     (__get_user(byte, (char __user *) pg) == 0)
 513                 && ((((u64)pg & PAGE_MASK) == (((u64)(pg + 1) - 1) & PAGE_MASK))
 514                         || (__get_user(byte, (char __user *) (pg + 1) - 1) == 0));
 515 }
 516 EXPORT_SYMBOL(ia64_pfn_valid);
 517
 518 int
 519 find_largest_hole (u64 start, u64 end, void *arg)
 520 {
 521         u64 *max_gap = arg;
 522
 523         static u64 last_end = PAGE_OFFSET;
 524
 525         /* NOTE: this algorithm assumes efi memmap table is ordered */
 526
 527         if (*max_gap < (start - last_end))
 528                 *max_gap = start - last_end;
 529         last_end = end;
 530         return 0;
 531 }
 532 #endif /* CONFIG_VIRTUAL_MEM_MAP */
 533
 534 static int
 535 count_reserved_pages (u64 start, u64 end, void *arg)
 536 {
 537         unsigned long num_reserved = 0;
 538         unsigned long *count = arg;
 539
 540         for (; start < end; start += PAGE_SIZE)
 541                 if (PageReserved(virt_to_page(start)))
 542                         ++num_reserved;
 543         *count += num_reserved;
 544         return 0;
 545 }
 546
 547 /*
 548  * Boot command-line option "nolwsys" can be used to disable the use of any light-weight
 549  * system call handler.  When this option is in effect, all fsyscalls will end up bubbling
 550  * down into the kernel and calling the normal (heavy-weight) syscall handler.  This is
 551  * useful for performance testing, but conceivably could also come in handy for debugging
 552  * purposes.
 553  */
 554
 555 static int nolwsys;
 556
 557 static int __init
 558 nolwsys_setup (char *s)
 559 {
 560         nolwsys = 1;
 561         return 1;
 562 }
 563
 564 __setup("nolwsys", nolwsys_setup);
 565
 566 void
 567 mem_init (void)
 568 {
 569         long reserved_pages, codesize, datasize, initsize;
 570         pg_data_t *pgdat;
 571         int i;
 572         static struct kcore_list kcore_mem, kcore_vmem, kcore_kernel;
 573
 574         BUG_ON(PTRS_PER_PGD * sizeof(pgd_t) != PAGE_SIZE);
 575         BUG_ON(PTRS_PER_PMD * sizeof(pmd_t) != PAGE_SIZE);
 576         BUG_ON(PTRS_PER_PTE * sizeof(pte_t) != PAGE_SIZE);
 577
 578 #ifdef CONFIG_PCI
 579         /*
 580          * This needs to be called _after_ the command line has been parsed but _before_
 581          * any drivers that may need the PCI DMA interface are initialized or bootmem has
 582          * been freed.
 583          */
 584         platform_dma_init();
 585 #endif
 586
 587 #ifndef CONFIG_DISCONTIGMEM
 588         if (!mem_map)
 589                 BUG();
 590         max_mapnr = max_low_pfn;
 591 #endif
 592
 593         high_memory = __va(max_low_pfn * PAGE_SIZE);
 594
 595         kclist_add(&kcore_mem, __va(0), max_low_pfn * PAGE_SIZE);
 596         kclist_add(&kcore_vmem, (void *)VMALLOC_START, VMALLOC_END-VMALLOC_START);
 597         kclist_add(&kcore_kernel, _stext, _end - _stext);
 598
 599         for_each_pgdat(pgdat)
 600                 if (pgdat->bdata->node_bootmem_map)
 601                         totalram_pages += free_all_bootmem_node(pgdat);
 602
 603         reserved_pages = 0;
 604         efi_memmap_walk(count_reserved_pages, &reserved_pages);
 605
 606         codesize =  (unsigned long) _etext - (unsigned long) _stext;
 607         datasize =  (unsigned long) _edata - (unsigned long) _etext;
 608         initsize =  (unsigned long) __init_end - (unsigned long) __init_begin;
 609
 610         printk(KERN_INFO "Memory: %luk/%luk available (%luk code, %luk reserved, "
 611                "%luk data, %luk init)\n", (unsigned long) nr_free_pages() << (PAGE_SHIFT - 10),
 612                num_physpages << (PAGE_SHIFT - 10), codesize >> 10,
 613                reserved_pages << (PAGE_SHIFT - 10), datasize >> 10, initsize >> 10);
 614
 615
 616         /*
 617          * For fsyscall entrpoints with no light-weight handler, use the ordinary
 618          * (heavy-weight) handler, but mark it by setting bit 0, so the fsyscall entry
 619          * code can tell them apart.
 620          */
 621         for (i = 0; i < NR_syscalls; ++i) {
 622                 extern unsigned long fsyscall_table[NR_syscalls];
 623                 extern unsigned long sys_call_table[NR_syscalls];
 624
 625                 if (!fsyscall_table[i] || nolwsys)
 626                         fsyscall_table[i] = sys_call_table[i] | 1;
 627         }
 628         setup_gate();
 629
 630 #ifdef CONFIG_IA32_SUPPORT
 631         ia32_mem_init();
 632 #endif
 633 }